#include<bits/stdc++.h>
using namespace std;
using Int = long long;
template<typename T1,typename T2> inline void chmin(T1 &a,T2 b){if(a>b) a=b;}
template<typename T1,typename T2> inline void chmax(T1 &a,T2 b){if(a<b) a=b;}


template<typename T> 
map<T, Int> factorize(T x){
  map<T, Int> res;
  for(Int i=2;i*i<=x;i++){
    while(x%i==0){
      x/=i;
      res[i]++;
    }
  }
  if(x!=1) res[x]++;
  return res;
}

//INSERT ABOVE HERE

signed main(){
  Int n,k;
  cin>>n>>k;

  map<Int, Int> dp;
  auto calc2=
    [&](Int x)->Int{
      if(dp.count(x)) return dp[x];
      Int &res=dp[x];
      auto m=factorize(x);
      res=0;
      for(auto p:m) res+=p.second;
      return res;
    };
  
  auto calc=
    [&](Int x)->Int{     
      auto m=factorize(x);
      Int res=1;
      for(auto p:m) res*=p.second+1;
      return res;
    };
  
  Int ans=0,cnt=0;
  for(Int i=1;i<n;i++){
    if(calc2(__gcd(i,n))<k) continue;
    Int res=calc(i);
    //cout<<i<<" "<<res<<endl;
    if(res>cnt) ans=i,cnt=res;
  }  
    
  cout<<ans<<endl;
  return 0;
}